Field
Aspects of the present disclosure relate to semiconductor devices, and more particularly to a backside coupled symmetric varactor structure.
Background
The process flow for semiconductor fabrication of integrated circuits (ICs) may include front-end-of-line (FEOL), middle-of-line (MOL), and back-end-of-line (BEOL) processes. The front-end-of-line process may include wafer preparation, isolation, well formation, gate patterning, spacer, extension and source/drain implantation, silicide formation, and dual stress liner formation. The middle-of-line process may include gate contact formation. Middle-of-line layers may include, but are not limited to, middle-of-line contacts, vias or other layers within close proximity to the semiconductor device transistors or other like active devices. The back-end-of-line process may include a series of wafer processing steps for interconnecting the semiconductor devices created during the front-end-of-line and middle-of-line processes. Successful fabrication of modern semiconductor chip products involves an interplay between the materials and the processes employed.
Mobile radio frequency (RF) chip designs (e.g., mobile RF transceivers) have migrated to a deep sub-micron process node due to cost and power consumption considerations. The design complexity of mobile RF transceivers is further complicated by added circuit function to support communication enhancements. Further design challenges for mobile RF transceivers include analog/RF performance considerations, including mismatch, noise and other performance considerations. The design of these mobile RF transceivers includes the use of a voltage-controlled capacitance and/or a tunable capacitor (e.g., a varactor) to, for example, provide a voltage controlled oscillator. Varactors may also be known as variable capacitance diodes.